The reducing of power consumption is an important factor in the design of mobile devices. The aim is to prolong the time between occasions when the recharging of battery of the mobile device is needed. In addition to the optimization of radio communication over the air interface, in particular transmissions by the mobile device, an important component that has a significant effect on power consumption is the display. Modern smart phones are equipped with large displays. In order to save battery the display is switched off when a user of the mobile device is not actively using the device. Another benefit of switching the display off is the prevention of image burn-in.
Mobile devices are equipped increasingly often with accelerometers, magnetometers and satellite navigation receivers that enable a plethora of navigation and positioning services. A magnetometer together with an accelerometer enables the implementation of digital compass applications in mobile devices. Accelerometers enable, for example, the implementation of pedometer applications in mobile devices. Therefore, together with navigation and positioning applications accelerometers enable the implementation of a variety of sports applications. These applications may display information on the distance walked by the user together with the path walked. The information regarding the current position of the user may be indicated, for example, on a map displayed on the screen. The information may be constantly updated so that the user may follow his/her position and distance travelled on the mobile phone display. The user may unlock the mobile device by pressing a key and check the current information on the display.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known mobile devices.